Eaten Out of House and Home: Impacts of Grazing on Ground-Dwelling Reptiles in Australian Grasslands and Grassy Woodlands

Abstract

Large mammalian grazers can alter the biotic and abiotic features of their environment through their impacts on vegetation. Grazing at moderate intensity has been recommended for biodiversity conservation. Few studies, however, have empirically tested the benefits of moderate grazing intensity in systems dominated by native grazers. Here we investigated the relationship between (1) density of native eastern grey kangaroos, Macropus giganteus, and grass structure, and (2) grass structure and reptiles (i.e. abundance, richness, diversity and occurrence) across 18 grassland and grassy Eucalyptus woodland properties in south-eastern Australia. There was a strong negative relationship between kangaroo density and grass structure after controlling for tree canopy cover. We therefore used grass structure as a surrogate for grazing intensity. Changes in grazing intensity (i.e. grass structure) significantly affected reptile abundance, reptile species richness, reptile species diversity, and the occurrence of several ground-dwelling reptiles. Reptile abundance, species richness and diversity were highest where grazing intensity was low. Importantly, no species of reptile was more likely to occur at high grazing intensities. Legless lizards (Delma impar, D. inornata) were more likely to be detected in areas subject to moderate grazing intensity, whereas one species (Hemiergis talbingoensis) was less likely to be detected in areas subject to intense grazing and three species (Menetia greyii, Morethia boulengeri, and Lampropholis delicata) did not appear to be affected by grazing intensity. Our data indicate that to maximize reptile abundance, species richness, species diversity, and occurrence of several individual species of reptile, managers will need to subject different areas of the landscape to moderate and low grazing intensities and limit the occurrence and extent of high grazing.

Can we save large carnivores without losing large carnivore science?

“…Newsome et al, 2001;Fitzsimmons, 2007;Allen, 2011). A range of important geological and biophysical differences are also present, not the least of which are the markedly different herbivore types, densities, and land-use histories, which are also well-known to structure fauna communities through grazing-induced habitat changes independent of dingoes or other predators (Tiver and Andrew, 1997;Williams and Price, 2010;Parsons et al, 2012;Howland et al, 2014;Koerner and Collins, 2014). The cross-fence differences are obvious, but their causes are not.…”

Influence of Grazing Intensity on Swamp Plant Communities in the Tropical Montane Wetland Ecosystems, Nilgiris, Southern India

“…Grazing by large herbivores plays a key role in maintaining the diversity, structure and function of many terrestrial ecosystems (Dahwa et al, 2013;Howland et al, 2014;Freitas et al, 2014;Ingerpuu and Sarv, 2015). However, excessive grazing can result in the ecological disturbance of vulnerable grassland and wetland ecosystems leading to biodiversity loss and biological invasions (Milchunas and Lauenroth, 1993;Perevolotsky and Seligman, 1998;Marty, 2005;Dahwa et al, 2013).…”

“…For instance, high grazing intensity is strongly correlated with high plant mortality and low recruitment rates, leading to changes in community structure and loss of species diversity (Milchunas et al, 1988;Gordon et al, 2004;Mysterud, 2006). Biophysical and ecological changes imposed by high grazing intensity may also have potential negative consequences on biodiversity and ecosystem function (Belsky and Blumenthal, 1997;Jones, 2000;Howland et al, 2014). As a result, intermediate or moderate grazing intensity is the most commonly recommended level of grazing intensity for long-term management of grasslands as it has been shown to maintain optimum species diversity at local through to global scales (Fuhlendorf and Engle, 2004;Dorrough et al, 2004).…”

Immediate action required to prevent another Australian avian extinction: the King Island Scrubtit

“…Fig S3 in Supplementary material). Likewise, super-abundant marsupial herbivores can have strong effects on the structure of native vegetation (Howland et al 2014) and this is recognised as a major problem on King Island (Norton and Johannson 2010). Suppression of the understorey by browsing herbivores may diminish habitat quality for Scrubtits.…”